Question

Calculate the length of wire of cross section 0.50mm2and
resistivity 2.5 x 10-7 Ωm which is required tomake a
heater rated at 72W, 12V. If the resistance of the wireincreases
with increasing temperature, how does the power changewith time
when the heater is used to melt a mixture of ice andwater to bring
it to boiling point?